Conventionally, an acoustic generator represented by a piezoelectric speaker is known as small-sized and low-current drive acoustic equipment in which a piezoelectric body is used for an electro-acoustic conversion element. The acoustic generator is used, for example, as an acoustic generation device incorporated in a small-sized electronic apparatus such as a mobile computing device.
Generally, the acoustic generator, in which the piezoelectric body is used for the electro-acoustic conversion element, has a structure in which a piezoelectric element with an electrode made of a thin silver film and the like formed thereon, is attached to a metallic vibration plate by an adhesive. In a sound generation mechanism of the acoustic generator in which the piezoelectric body is used for the electro-acoustic conversion element, an alternate-current voltage is applied to both surfaces of the piezoelectric element so that the form distortion occurs in the piezoelectric element, and the form distortion of the piezoelectric element is transmitted to the metallic vibration plate and vibrates it, whereby sound is generated (for example, see Patent Literature 1 and 2).